Groups > comp.lang.java.programmer > #38405

Re: Has Android different floats?

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From	Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups	comp.lang.java.programmer
Subject	Re: Has Android different floats?
Date	Sun, 24 Jun 2018 17:28:58 -0400
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On 6/24/2018 4:35 PM, bursejan@gmail.com wrote:
> The test code would be:
> 
>          for (int i=22; i<25; i++) {
>             System.out.println("Math.pow(10,"+i+")="+Math.pow(10,i));
>          }
> 
> The result (without strictfp modifier to main()) is:
>     
>     Math.pow(10,22)=1.0E22
>     Math.pow(10,23)=1.0000000000000001E23
>     Math.pow(10,24)=1.0E24
> 
> The result (with strictfp modifier to main()) is:
> 
>     Math.pow(10,22)=1.0E22
>     Math.pow(10,23)=1.0000000000000001E23
>     Math.pow(10,24)=1.0E24
> 
> Because invoking Math.pow() is not a basic operator +, *, /, etc..

     Have you tried using StrictMath.pow() instead of Math.pow()?
It is certainly possible that the Math implementations are different
on different platforms -- at least, the Javadoc seems to allow such
freedom:

	"[...] Code generators are encouraged to use platform-specific
	native libraries or microprocessor instructions, where
	available, to provide higher-performance implementations of Math
	methods. [...]"

It's my understanding, though, that StrictMath implementations on all
platforms are supposed to agree exactly.

-- 
esosman@comcast-dot-net.invalid
Nine hundred forty-one days to go.

Thread

Has Android different floats? j4n bur53 <janburse@fastmail.fm> - 2018-06-24 20:41 +0200
  Re: Has Android different floats? Arne Vajhøj <arne@vajhoej.dk> - 2018-06-24 15:21 -0400
    Re: Has Android different floats? bursejan@gmail.com - 2018-06-24 13:31 -0700
      Re: Has Android different floats? bursejan@gmail.com - 2018-06-24 13:35 -0700
        Re: Has Android different floats? bursejan@gmail.com - 2018-06-24 13:44 -0700
        Re: Has Android different floats? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-06-24 17:28 -0400
          Re: Has Android different floats? bursejan@gmail.com - 2018-06-24 16:08 -0700
            Re: Has Android different floats? bursejan@gmail.com - 2018-06-26 10:29 -0700

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